The present study highlights the taxonomic values of the pollen features of 20
species of Verbascum L. in Iraq. The pollen grains were acetolysed and observed under
Light and Electron microscopes. Our results showed that the pollen grains of these
species are usually radially symmetrical, isopolar, tricolporate and display reticulate
sculpturing. The variations were found in shape, size, and exine thickness. Most of the
species are subprolate, prolate spheroidal, and prolate, whereas oblate spheroidal pollens
were found only in V. thapsus. The pollen size among the species studied ranges from
16.2-32.5 μm. The majority of species are medium sized except V. agrimoniifolium and
V. oreophilum that are small sized, and four species i.e. V. palmyrense, V. sinuatum, V.
songaricum, and V. thapsus having both small and medium sized pollen grains.
Moreover, the result showed that the exine thickness ranges from 0.87-4.75 μm, but this
value can overlap between some species. Therefore, only the shape of pollen grains
could be used to classify these species into groups.